1. Technical Field
The present invention relates to wireless communications and, more particularly, to beamforming methods and systems.
2. Description of the Related Art
The proliferation of mobile devices has increased the demand for applications (streaming media, software updates, etc.) and services (location-based, social networking, etc.) involving group communications. To support such applications, designs of efficient link layer wireless multicasting solutions are needed. The advancement in antenna array technology and the associated mechanisms that it enables (MIMO, beamforming, etc.) have become a standard feature in next generation broadband access networks (WiMAX, LTE-Adv). In beamforming, the signal is transmitted using a beam pattern that reinforces the signal towards the desired client, while minimizing the leakage of signal power in undesired directions. Given that the multicast performance is largely determined by the bottleneck client (with poor channel conditions) in the group, beamforming is an attractive candidate for multicasting, as it can improve the channel conditions of the bottleneck client. However, a beamforming vector optimized for one client may not be effective for another client. Given that multiple clients should be served simultaneously in multicast systems, an effective solution should balance the beamforming benefits with the ability to effectively cover multiple clients.